A separated type telephone is known that is a telephone separated into an external communication function and an operation function, which are implemented as a parent device and a child device, respectively. Since the function of the parent device and the function of the child device are independently utilized in the separated state, such a telephone is equipped with individual power supply and performs control thereof.
With regard to such power supply control, in a portable telephone separated into a telephone body and a display operating unit, it is known that a main power switch of the telephone body controls the power-on/off in conjunction with control of a power switch of the display operating unit (Japanese Laid-Open Patent Publication No. 2004-172826).